Field of the Invention
The present invention relates to a method of fabricating a light-emitting diode (LED) package. More particularly, the present invention relates to a method of fabricating an LED package that does not require an additional heat treatment or cutting process on a color conversion frit after bonding the color conversion frit to an LED chip.
Description of Related Art
A light emitting diode (LED) is a semiconductor device formed of a compound such as gallium arsenide (GaAs) to emit light in response to an electrical current applied thereto. The LED uses a p-n junction semiconductor structure into which minority carriers, such as electrons or holes, are injected, such that light is generated by the recombination of electrons and holes.
The characteristics of LEDs include low power consumption, a relatively long lifespan, the ability to be mounted in cramped spaces, and strong resistance to vibrations. While LEDs are used in display devices and the backlight units of display devices, studies into applying LEDs to general lighting devices have been recently undertaken. In addition to monochromatic LEDs, such as red, blue, or green LEDs, white LEDs have also come onto the market. In particular, a sharp increase in demand for white LEDs is expected, since white LEDs can be applied to vehicle lighting devices and general lighting apparatuses.
In the field of LED technology, white light is commonly generated using two main methods. The first method to generate white light includes disposing monochromatic LEDs, such as red, green, and blue LEDs, adjacently to each other such that various colors of light emitted by the monochromatic LEDs are mixed. However, color tones may change depending on the environment in which such devices are used, since individual monochromatic LEDs have different thermal or temporal characteristics. In particular, color stains may occur, making it difficult to uniformly mix different colors of light. The second method to generate white light includes applying a fluorescent material to surfaces of an LED and mixing a portion of light initially emitted by the LED and secondary light wavelength-converted by the fluorescent material. For example, a fluorescent material generating yellowish-green or yellow light may be used as a light excitation source on a blue LED, whereby white light can be produced by mixing blue light emitted by the blue LED and yellowish-green or yellow excitation light from the fluorescent material. At present, the second method of realizing white light utilizing a blue LED and a fluorescent material is generally used.
The fluorescent material for producing white light in cooperation with the blue LED chip can be used mixed with a frit. In the related art, in order to directly bond the mixture of the frit and the fluorescent material to the LED chip, the mixture of the frit and the fluorescent material has been formed into a paste, followed by coating the LED chip with the mixture of the frit and the fluorescent material and subsequent sintering. However, the sintering temperature is commonly 500° C. or above, and the LED chip that is thermally stable at 200° C. or below cannot withstand such a sintering temperature. That is, sintering the mixture of the frit and the fluorescent material at such a temperature will degrade LED chips, which is problematic. In addition, a heat treatment, such as sintering, performed after the operation of coating the LED chip with the mixture of the frit and the fluorescent material may cause a problem. For example, a base substrate, i.e. a GaN substrate, on which a plurality of LEDs is formed, may be warped. When a GaN substrate is warped in this manner, none of the plurality of LED chips formed on the GaN substrate can be used. Although a fluorescent mixture able to be sintered at a low temperature may be used in order to overcome the degradation problem, other problems, such as peeling or fracturing, may occur in the process of cutting the plurality of LED chips.